Question

我正在制作一个应用程序，这个应用程序的一个功能是从数据库中删除一个条目，我使用条目的rowid正确工作，但现在我希望用户能够使用一个删除行列名。我现在的代码是我认为会起作用的，但它给了我一个错误，有人可以帮忙吗？

这是我正在使用的删除类：

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import com.pinchtapzoom.R;


public class Delete extends Activity implements View.OnClickListener{

public EditText item;
Button delete;

//instansiation the DBAdapter class to db, to call functions from DBApater use db.(function name)
DBAdapter db = new DBAdapter(this);


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_delete);

    item = (EditText)findViewById(R.id.edit1);
    delete = (Button)findViewById(R.id.delete);

    delete.setOnClickListener(this);

    }


public void onClick(View v) {

    String deleteItem = item.getText().toString();

    //if the ROW ID its a number (long)
    try{
        //long rowID = Long.parseLong(userInput);
        //call the delete method
        db.open();
        db.deleteContact(deleteItem);
        db.close();
        Toast.makeText(Delete.this,"Item Deleted", Toast.LENGTH_SHORT).show();

    }catch(NumberFormatException e){
        Log.e("INPUT ERROR","Input is not a number!",e);
        Toast.makeText(this,"Invalid Value!",Toast.LENGTH_LONG).show();
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.delete, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}

//returns to home screen, set on the button in xml
public void viewAssignments(View v)
{
    Intent i = new Intent(this, MyActivity.class);
    startActivity(i);
}
}

这是我在数据库类中调用的函数

//---deletes a particular record---
public boolean deleteContact(String item)
{
    return db.delete(DATABASE_TABLE, KEY_ITEM + "=" + item, null) > 0;
}

我运行时的logcat错误是

Process: com.example.rory.dbtest, PID: 8165
android.database.sqlite.SQLiteException: no such column: shower (code 1): , while compiling: DELETE  FROM assignments WHERE item=shower
        at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
        at  android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889)
        at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500)
        at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
        at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
        at android.database.sqlite.SQLiteStatement.<init>(SQLiteStatement.java:31)
        at android.database.sqlite.SQLiteDatabase.delete(SQLiteDatabase.java:1494)
        at com.example.rory.dbtest.DBAdapter.deleteContact(DBAdapter.java:91)
        at com.example.rory.dbtest.Delete.onClick(Delete.java:48)

Answer 1

试试这个

return db.delete(DATABASE_TABLE, KEY_ITEM + "=\"" + item + "\"", null) > 0;

从SQLite数据库中删除条目

1 个答案: